Liquid chromatography-mass samples

A liquid chromatography-mass spectrometry (LC-MS) method that can quantitatively analyze urinar y normal and modified nucleosides in less than 30 min with a good resolution and sufficient sensitivity has been developed. Nineteen kinds of normal and modified nucleosides were determined in urine samples from 10 healthy persons and 18 breast cancer patients. Compounds were separ ated on a reverse phase Kromasil C18 column (2.1 mm I.D.) by isocratic elution mode using 20 mg/1 ammonium acetate - acetonitrile (97 3 % v/v) at 200 p.l/min. A higher sensitivity was obtained in positive atmospheric pressure chemical ionization mode APCI(-i-). 

Farre M, Ferrer I, Ginebreda A, Figueras M, Olivella L, Tirapu L, Vilanova M, Barcelo D (2001) Determination of drugs in surface water and wastewater samples by liquid chromatography-mass spectrometry methods and preliminary results including toxicity studies with Vibrio fischeri. J Chromatogr A 938 187-197... 

Betowski LD, Jones TL. 1988. Analysis of organophosphoms pesticide samples by high-performance liquid chromatography/mass spectrometry and high-performance liquid chromatography/mass spectrometry/mass spectrometry. Environ Sci Technol 22 1430-1434. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

More recently, liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) have been evaluated as possible alternative methods for carfentrazone-ethyl compounds in crop matrices. The LC/MS methods allow the chemical derivatization step for the acid metabolites to be avoided, reducing the analysis time. These new methods provide excellent sensitivity and method recovery for carfentrazone-ethyl. However, the final sample extracts, after being cleaned up extensively using three SPE cartridges, still exhibited ionization suppression due to the matrix background for the acid metabolites. Acceptable method recoveries (70-120%) of carfentrazone-ethyl metabolites have not yet been obtained. 

The need to understand the fate of pesticides in the environment has necessitated the development of analytical methods for the determination of residues in environmental media. Adoption of methods utilizing instrumentation such as gas chro-matography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS), or enzyme-linked immunosorbent assay (ELISA) has allowed the detection of minute amounts of pesticides and their degradation products in environmental samples. Sample preparation techniques such as solid-phase extraction (SPE), accelerated solvent extraction (ASE), or solid-phase microextraction (SPME) have also been important in the development of more reliable and sensitive analytical methods. 

E. M. Thurman and C. Batian, Determination of atrazine and atrazine mercapture in drinking water samples and in urine using immunoaffinity SPE with positive ion spray HPLC/MS , Presented at the 15th Symposium on Liquid Chromatography/Mass Spectrometry, Montreux, Switzerland, November 9-10, 1998. 

For method tryout, run a control sample and two fortifications from each site. One fortification should be done at the LOQ and the other at the highest expected residue level, perhaps 1000 x LOQ. If the recoveries are within the acceptable range of 70-120% and there are no interferences, proceed with the method validation. If interferences are present which prevent quantitation of the analyte, try additional cleanup steps with SPE or use a more selective detection method such as liquid chromatography/mass spectrometry (LC/MS). 

Two variations on the analysis of PCR products by ESI mass spectrometry have emerged (1) direct-injection MS and tandem mass spectrometry (MS-MS) and (2) liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS). In the former approach, the sample is cleaned manually, and as noted above, the cleanup is performed as simply and rapidly as possible. In the latter approach, the cleanup is done automatically... 

Petrovic M, Farre M, de Alda ML, Perez S, Postigo C, Kock M, Radjenovic J, Gros M, Barcelo D (2010) Recent trends in the liquid chromatography-mass spectrometry analysis of organic contaminants in environmental samples. J Chromatogr A 1217(25) 4004 1017... 

The use of direct UV spectrophotometry to measure sample concentrations in pharmaceutical research is uncommon, presumably due to the prevalence and attractiveness of high-performance liquid chromatography (HPLC) and liquid chromatography/mass spectrometry (LC/MS) methods. Consequently, most researchers are unfamiliar with the value of UV detection, mainly that it is generally much faster than other methods - a very important asset in high-throughput screening. 

Ferrer and Barcelo [131] used online solid-phase-liquid chromatography mass spectrometry for the simultanous determination of organotin antifouling herbicides in marine water. The solid-phase extraction was carried out on polymeric cartridges after percolation of 100 ml of the seawater sample, and... 

This chapter will review recent advances in mass spectrometry, liquid chromatography, and sample preparation techniques that aim at achieving high throughput. In particular, online solid phase extraction and multiplexed HPLC front ends for quantitative bioanalysis will be discussed in detail. 

Ferrer I. and Barcelo, D., 1999. Simultaneous determination of antifouling herbicides in marina water samples by online solid-phase extraction followed by liquid chromatography-mass spectrometry. J Chromatogr A 854 197. 

Lant M.S. and Oxford J., 1987. Automated sample preparation online with thermospray high-performance liquid chromatography-mass spectrometry for the determination of drugs in plasma. J Chromatogr A 394 223. 

Recent studies, including the use of Microtox and ToxAlert test kits [55,56], were carried out for the determination of the toxicity of some non-ionic surfactants and other compounds (aromatic hydrocarbons, endocrine disruptors) before implementation on raw and treated wastewater, followed by the identification and quantification of polar organic cytotoxic substances for samples with more than 20% inhibition. Furthermore, the study of their contribution to the total toxicity was obtained using sequential solid-phase extraction (SSPE) before liquid chromatography-mass spectrometry (LC-MS) detection. This combined procedure allows one to focus only on samples containing toxic substances. 

This technique is complementary to the thermospray technique. Relative advances of the particles beam technique over thermospray include library searchable electron impact spectra, improved reproducibility, easier use and increased predictability over a broad range of compounds. But since a particle beam requires same sample volatility, very large and polar compounds such as proteins may not provide satisfactory results using particle beam liquid chromatography-mass spectrometry. Additionally, certain classes of compounds such as preformed ions, azo dyes and complex sugars may not yield satisfactory electron impact spectra, but can be run on thermospray. In other words, both liquid chromatography-mass spectrometry techniques complement each other s limitations and the analyst may want to add both to address a broader range of samples. 

H.Fr. Schroder, Determination of Fluorinated Surfactants and their Metabolites in Sewage Sludge Samples by Liquid Chromatography-Mass Spectrometry and -Tandem Mass Spectrometry after Pressurised Solvent Extraction and Separation on Fluorine Modified RP-Phases, J. Chromatogr. A, in press. 

Puig et al. [450] determined ng/1 levels of priority methyl-, nitro-, and chloro-phenols in river water samples by an automated on-line SPE technique, followed by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI) and ion spray interfaces. 

Of particular note is liquid chromatography/mass spectrometry (LC/MS) detection. LC/M S technology is a critical technique for DMPK studies due to its ability to analyze samples with very high sensitivity and specificity particularly within complex mixtures. It is not uncommon to find LC/MS based sample analysis residing within its own functional department due to the specialized facility requirements and technical skills of the operators. Additionally with LC/MS instrumentation becoming lower cost and simpler to operate, they are also becoming a workhorse... 

Liquid chromatography/mass spectrometry analyses were performed with an ion trap mass spectrometer (LCQ, Thermo Fisher Scientific Inc., MA) equipped with an HPLC system (Agilent, CA Model 1100) connected with a diode-array detector (DAD, G1315A). The sample solution (1-5 p,L) was applied on an Inertsil ODS-3 column (2.1 x 150 mm, 3 p,m, GL... 

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